This invention is directed to thermoplastic polymer monofilaments containing a flake additive to provide monofilaments having an attractive glitter that are useful in brushes such as tooth brushes and cosmetic brushes.
Polyamide monofilaments have been used widely for bristles in brushes such as cosmetics brushes and tooth brushes. Abrasive materials have been incorporated into monofilaments that are used as bristles in tooth brushes as shown in U.S. Pat. No. 5,722,106 issued on Mar. 3, 1998 to Masterman et al. These abrasive materials are usually small particles (0.1-10 microns) but are not visible as distinct particles and are used in relatively high amounts such as 10-40% by weight of the monofilament. However, these particles do not provide an attractive glitter to the monofilaments and the monofilaments are often much more abrasive than needed.
Particles of plastic materials that are relatively thermally stable also have been incorporated into monofilaments that are used as bristles in tooth brushes to produce bristles with a structured surface that is mildly abrasive as shown in WO 97/09906 published Mar. 20, 1997. These particles of plastic materials are usually blended at a level of 5-30% by weight of the total weight of the filament and are limited to 10-50% of the diameter of the filament. These particles often cause breakage in the filament during processing.
There is a need for monofilaments that have an attractive appearance for use in tooth brushes and other brush applications that are only mildly abrasive and contain a relatively small amount of the abrasive material and are stronger and more wear resistant than those previously made. The monofilaments of the present invention provide such advantages.